JPH0532231U - Power steering device - Google Patents

Abstract

(57) [Summary] [Structure] At least one of the input shaft 3 interlocked with the steering wheel and the output shaft 4 interlocked with the steering wheel is formed with through holes 3a, 4a penetrating the axis. By the torsion bar 8 inserted into the through holes 3a and 4a, the input shaft 3 and the output shaft 4 are
And are connected. An assisting force for steering operation is applied according to the twist of the torsion bar 8 due to the torque transmitted from the input shaft 3 to the output shaft 4. A female screw 50 is formed on the inner circumference of the through hole 4a of at least one of the shafts 4, and a male screw 51 is screwed onto the female screw 50, and the male screw 51 supports the end face of the torsion bar 8. [Effect] Even when an impact force is applied to the input / output shaft, an appropriate steering assist force can be applied according to the torsion of the torsion bar.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is a power steering device in which an input shaft that is interlocked with a steering wheel and an output shaft that is interlocked with steering wheels are connected by a torsion bar, and a steering assisting force is applied according to the torsion of the torsion bar. Regarding

[0002]

[Prior Art]

 Power to give steering assist force according to the magnitude of torque transmitted from the input shaft to the output shaft when transmitting the rotation of the handle from the input shaft to the steering wheel via the output shaft. There is a steering device.

For example, an electric power steering device 101 shown in FIG. 3 includes an input shaft 103 and an output shaft 104 which are supported inside a housing 102 via bearings. The input shaft 103 and the output shaft 104 are respectively formed with through holes 103a and 104a penetrating the centers thereof, and the torsion bar 105 is inserted into the through holes 103a and 104a. The torsion bar 105 and the output shaft 104 are connected by inserting a pin 121 into one end of the torsion bar 105 and the output shaft 104. The other end of the torsion bar 105 is press-fitted into a recess 122a formed on the rotary shaft 122 of the vehicle handle. The rotary shaft 122 is inserted into the through hole 103a of the input shaft 103, and the end face of the rotary shaft 122 abuts on a step portion 103a 'formed on the inner circumference of the through hole 103a. The pin 123 is inserted into the other end of the torsion bar 105, the input shaft 103, and the rotary shaft 122 to connect the torsion bar 105, the input shaft 103, and the rotary shaft 122.

A worm wheel 125 is fitted on the outer periphery of the output shaft 104, and this gear 125 is meshed with a worm 126 attached to the output shaft of the steering assist motor not shown.

A sleeve 106 made of a non-magnetic material is fitted to the outer circumference of the input shaft 103, and a first detection ring 107 made of a magnetic material is fitted to the outer circumference of the sleeve 106. A second detection ring 108 made of a magnetic material is fitted around the output shaft 104. The first detection ring 107 and the second detection ring 108 are arranged so as to face each other, and a plurality of teeth 109, 110 are formed on the facing end faces of the respective detection rings 107, 108 along the circumferential direction. Further, the third detection ring 111 is fitted on the input shaft 103. The third detection ring 111 and the first detection ring 107 are arranged so as to face each other, and a plurality of teeth 112 are formed on the facing end surface of the third detection ring 111 along the circumferential direction.

A first detection coil 114 and a second detection coil 116 are provided inside the housing 102. The first detection coil 114 is arranged so as to cover the opposite ends of the first detection ring 107 and the second detection ring 108, and the second detection coil 116 is arranged to cover the first detection ring 107 and the third detection ring. It is arranged so as to cover the end opposite to 111.

As shown in FIG. 4, the first detection coil 114 is connected to the oscillator 118 via a resistor 117, and the second detection coil 116 is connected to the oscillator 118 via a resistor 119. The first detection coil 114 is connected to the inverting input terminal of the operational amplifier 120, and the second detection coil 116 is connected to the non-inverting input terminal of the operational amplifier 120. As a result, the first detection coil 114 generates a magnetic flux that passes through the first detection ring 107 and the second detection ring 108, and the second detection coil 116 generates a magnetic flux that passes through the first detection ring 107 and the third detection ring 111. Occur. Then, when the torsion bar 105 is twisted by the torque transmission from the input shaft 103 to the output shaft 104, the first detection ring 107 and the second detection ring 108 relatively rotate about the shaft center. As a result, the area of the overlapping portions of the teeth 109 and 110 provided at the opposite ends of the first detection ring 107 and the second detection ring 108 in the axial direction changes, and thus the impedance of the system changes, The output voltage of the detection coil changes according to the change. This change in output voltage is amplified by the operational amplifier 120, and an electric signal corresponding to the transmission torque is obtained. The steering assist motor is driven in response to this signal, and steering assist force is applied to the output shaft 104 via the worm 126 and the worm wheel 125.

Further, even if the impedance on the first detection coil 114 side changes due to the temperature change, the impedance on the second detection coil 116 side also changes due to the temperature change, and the output fluctuation due to the temperature change of each detection coil 114, 116. Is canceled by the operational amplifier 120. Thereby, the torque detection by the first detection coil 114 is compensated so as not to be influenced by temperature.

[0009]

[Problems to be solved by the device]

 In the conventional power steering device 101, the axial relative movement of the torsion bar 105 with respect to the output shaft 104 is prevented only by the pin 121. Therefore, when the power steering device 101 is accidentally dropped during assembling to a vehicle or during transportation and an axial impact force acts on the input shaft 103 or the output shaft 104, the output shaft 104 and the torsion bar 105 are connected. The pin 121 may be deformed, and the facing distance between the first detection ring 107 attached to the input shaft 103 and the second detection ring 108 attached to the output shaft 104 may be reduced. Then, the center value of the output voltage corresponding to the torque transmitted from the input shaft 103 to the output shaft 104 is deviated, and it becomes impossible to apply an appropriate steering assist force according to the torsion of the torsion bar. Cause

An object of the present invention is to provide a power steering device that can solve the above-mentioned problems of the prior art.

[0011]

[Means for Solving the Problems]

 A feature of the present invention is that at least one of an input shaft that interlocks with a steering wheel and an output shaft that interlocks with a steering wheel has a through hole penetrating the shaft center, and a torsion bar inserted into the through hole forms a through hole. In a power steering system in which an input shaft and an output shaft are connected to each other, an assisting force for steering operation is applied according to the torsion of the torsion bar due to the torque transmitted from the input shaft to the output shaft, the through hole of at least one shaft. A female screw is formed on the inner circumference of the, and a male screw is screwed onto this female screw, and the end face of the torsion bar is supported by this male screw.

[0012]

[Action]

 According to the configuration of the present invention, the axial relative movement of at least one of the input shaft and the output shaft and the torsion bar can be blocked by the male screw screwed into the through hole of the one shaft.

[0013]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

The power steering device 1 shown in FIG. 1 includes a housing 2, an input shaft 3, and an output shaft 4.

The input shaft 3 is rotatably supported inside the housing 2 via a bearing 5, and is connected to a rotating shaft 9 of a steering wheel of the vehicle. The output shaft 4 is rotatably supported inside the housing 2 via bearings 6a and 6b, and is interlocked with a steering wheel not shown. The input shaft 3 and the output shaft 4 are connected by a torsion bar 8 inserted in through holes 3a, 4a penetrating the shaft centers of the shafts 3, 4. That is, by inserting the pin 61 into one end of the torsion bar 8 and the output shaft 4, the torsion bar 8 and the output shaft 4 are connected. The other end of the torsion bar 8 is press-fitted in a recess 62 formed at the end of the rotating shaft 9. The end of the rotary shaft 9 is inserted into the through hole 3a of the input shaft 3, and the end face abuts on the stepped portion 3a 'formed on the inner circumference of the through hole 3a. The pin 60 is inserted into the other end of the torsion bar 8, the input shaft 3 and the rotating shaft 9, so that the torsion bar 8, the input shaft 3 and the rotating shaft 9 are connected.

A worm wheel 10 is fitted on the outer circumference of the output shaft 4, and the worm wheel 10 is meshed with a worm 11 attached to the output shaft of the steering assist motor not shown.

A sleeve 12 made of a non-magnetic material is inserted into the outer circumference of the input shaft 3, and a first detection ring 13 made of a magnetic material is press-fitted into the outer circumference of the sleeve 12. The sleeve 12 and the first detection ring 13 are fixed to the input shaft 3 by press-fitting the plurality of pins 7 into the input shaft 3, the sleeve 12, and the first detection ring 13. A second detection ring 14 made of a magnetic material is press-fitted onto the outer circumference of the output shaft 4. The second detection ring 14 is arranged so as to face the first detection ring 13. A plurality of teeth 13a and 14a are provided on the opposing end faces of the respective detection rings 13 and 14 along the circumferential direction. A third detection ring 15 made of a magnetic material is press-fitted on the outer circumference of the input shaft 3. The first detection ring 13 is arranged between the third detection ring 15 and the second detection ring 14. A plurality of teeth 15 a are provided along the circumferential direction on the end surface of the third detection ring 15 that faces the first detection ring 13.

A first cylindrical holder 16 made of a magnetic material is inserted inside the housing 2, and a first detection coil 17 is inserted inside the first cylindrical holder 16. At both axial ends of the first cylindrical holder 16, magnetic material covers 18 and 19 are provided to cover both axial ends of the first detection coil 17. The first detection coil 17 is arranged so as to cover opposite ends of the first detection ring 13 and the second detection ring 14. A second cylindrical holder 20 made of a magnetic material is inserted inside the housing 2, and a second detection coil 21 is inserted inside the second cylindrical holder 20. Covers 22 and 23 made of magnetic material that cover both axial ends of the second detection coil 21 are provided at both axial ends of the second cylindrical holder 20. The second detection coil 21 is arranged so as to cover the opposite ends of the first detection ring 13 and the third detection ring 15.

A leaf spring 31 is interposed between the first cylindrical holder 16 and a ring-shaped stopper 30 fitted to the inner circumference of the housing 2. Further, the distance piece 32 is arranged between the first cylindrical holder 16 and the second cylindrical holder 20, and the distance piece 33 is arranged between the second cylindrical holder 20 and the inner surface of the housing 2. There is. This prevents axial movement of the cylindrical holders 16 and 20.

As shown in FIG. 2, the first detection coil 17 is connected to the oscillator 43 via the resistor 42, and the second detection coil 21 is connected to the oscillator 43 via the resistor 44. The first detection coil 17 is connected to the inverting input terminal of the operational amplifier 45, and the second detection coil 21 is connected to the non-inverting input terminal of the operational amplifier 45. As a result, the first detection coil 17 generates a magnetic flux passing through the first detection ring 13 and the second detection ring 14, and the second detection coil 21 passes through the first detection ring 13 and the third detection ring 15. Generates magnetic flux. Then, when the torsion bar 8 is twisted by the torque transmission from the input shaft 3 to the output shaft 4, the first detection ring 13 and the second detection ring 14 relatively rotate about the shaft center. Then, the area of the overlapping portions of the teeth 13a and 14a formed on the opposite end faces of the first detection ring 13 and the second detection ring 14 with respect to the axial direction changes, and the impedance of the system changes. Accordingly, the output voltage of the first detection coil 17 changes. This change in output voltage is amplified by the operational amplifier 45, and an electric signal corresponding to the transmission torque is obtained. The steering assist motor is driven in response to this signal, and steering assist force is applied to the output shaft 4 via the worm 11 and the worm wheel 10.

Further, even if the impedance on the side of the first detection coil 17 changes due to the temperature change, the impedance on the side of the second detection coil 21 also changes due to the temperature change, and the output fluctuation due to the temperature change of each detection coil 17, 21 It is canceled by the operational amplifier 45. As a result, the torque detection by the first detection coil 17 is compensated so as not to be affected by temperature.

A female screw 50 is formed on the lower end of the inner circumference of the through hole 4 a of the output shaft 4, and a male screw 51 is screwed onto the female screw 50. The male screw 51 has a small diameter portion 51a and a large diameter portion 51b, a thread is formed on the outer periphery of the large diameter portion 51b, and a hexagonal hole 51c for inserting a tool is formed on the end surface of the large diameter portion 51b. .. The lower end surface 51 a ′ of the small diameter portion 51 a of the male screw 51 is brought into contact with the lower end surface 8 a of the torsion bar 8 so that the lower end surface of the torsion bar 8 is supported by the male screw 51. Before the male screw 51 is screwed onto the female screw 50, an adhesive is applied to the male screw 51 to prevent the male screw 51 from coming off after screwing.

According to the above configuration, even if the power steering device 1 is accidentally dropped and an axial impact force is applied to the input shaft 3 and the output shaft 4, one end of the torsion bar 8 has a recess 62 of the rotary shaft 9. Since the rotary shaft 9 is press-fitted into the rotary shaft 9 and is in contact with the step portion 3a 'of the through hole 3a of the input shaft 3, the torsion bar 8 and the input shaft 3 do not move in the axial direction. Since the other end surface 8a of the torsion bar 8 is supported by the male screw 51, the relative movement of the torsion bar 8 and the output shaft 4 in the axial direction is prevented not only by the pin 61 but also by the male screw 51, and the input / output is performed. Even if an impact force is applied to the shafts 3 and 4, the pin 61 is not deformed. As a result, the torsion bar 8 and the input / output shafts 3 and 4 do not move in the axial direction, and the facing distance between the first detection ring 13 and the second detection ring 14 does not change. Therefore, the deviation of the center value of the output voltage depending on the torque transmitted from the input shaft 3 to the output shaft 4 is prevented, and an appropriate steering assist force according to the twist of the torsion bar 8 can be applied.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the output shaft is screwed with a male screw to support the end face of the torsion bar.However, the input shaft may be screwed with a male screw to support the end face of the torsion bar, or the input shaft is supported. The male and female output shafts may be screwed in to support both ends of the torsion bar. Further, although the present invention is applied to the electric power steering device in the above embodiment, the steering assist force is applied by operating the hydraulic control valve according to the torsion of the torsion bar due to the torque transmitted from the input shaft to the output shaft. The present invention can also be applied to a hydraulic power steering device that operates.

[0025]

[Effect of the device]

 According to the power steering device of the present invention, relative axial movement of at least one of the input shaft and the output shaft and the torsion bar can be prevented more reliably than before, so that an impact force is applied to the input / output shaft. Even if it acts, the pin connecting the input / output shaft and the torsion bar does not deform, and the center value of the output voltage corresponding to the torque does not shift, so an appropriate steering assist force is applied according to the torsion of the torsion bar. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view of a power steering device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a circuit configuration of a power steering device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a power steering device according to a conventional example.

FIG. 4 is an explanatory diagram of a circuit configuration of a power steering device according to a conventional example.

[Explanation of symbols]

 2 Housing 3 Input shaft 3a Through hole 4 Output shaft 8 Torsion bar 50 Female screw 51 Male screw

Claims (1)

[Scope of utility model registration request] 1. A through hole penetrating the shaft center is formed in at least one of an input shaft interlocking with a handle and an output shaft interlocking with a steering wheel, and a torsion bar inserted into the through hole forms an input shaft and an output. In a power steering device that is connected to a shaft and is provided with an assisting force for steering operation according to the torsion of the torsion bar due to the torque transmitted from the input shaft to the output shaft, at least the inner circumference of the through hole of the shaft A power steering device characterized in that a female screw is formed, a male screw is screwed onto the female screw, and the end face of the torsion bar is supported by the male screw.